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- Title
The expression of nifB gene from Herbaspirillum seropedicae is dependent upon the NifA and RpoN proteins.
- Authors
Rego, Fabiane G. M.; Pedrosa, Fábio O; Chubatsu, Leda S.; Yates, M. Geoffrey; Wassem, Roseli; Steffens, Maria B. R.; Rigo, Liu U.; Souza, Emanuel M.
- Abstract
The putative nifB promoter region of Herbaspirillum seropedicae contained two sequences homologous to NifA-binding site and a –24/–12 type promoter. A nifB::lacZ fusion was assayed in the backgrounds of both Escherichia coli and H. seropedicae. In E. coli, the expression of nifB::lacZ occurred only in the presence of functional rpoN and Klebsiella pneumoniae nifA genes. In addition, the integration host factor (IHF) stimulated the expression of the nifB::lacZ fusion in this background. In H. seropedicae, nifB expression occurred only in the absence of ammonium and under low levels of oxygen, and it was shown to be strictly dependent on NifA. DNA band shift experiments showed that purified K. pneumoniae RpoN and E. coli IHF proteins were capable of binding to the nifB promoter region, and in vivo dimethylsulfate footprinting showed that NifA binds to both NifA-binding sites. These results strongly suggest that the expression of the nifB promoter of H. seropedicae is dependent on the NifA and RpoN proteins and that the IHF protein stimulates NifA activation of nifB promoter.
- Subjects
GENE expression; ESCHERICHIA coli; BIOMOLECULES; DETERMINATIVE mineralogy; PHOTOSYNTHETIC oxygen evolution; BACTERIAL proteins; BACTERIAL genetics; HEREDITY
- Publication
Canadian Journal of Microbiology, 2006, Vol 52, Issue 12, p1199
- ISSN
0008-4166
- Publication type
Article
- DOI
10.1139/W06-085